1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to a method and apparatus for efficient acquisition of preambles with enhanced interference mitigation.
2. Background
Wireless communications technology has penetrated nearly every aspect of a person's daily routine. Integrated into almost every conceivable electronic device to facilitate business activities as well as personal uses such as entertainment, medicine, and exercise, wireless systems are widely deployed to provide various types of communication content such as voice, data, video, and so on. One type of wireless system technology, referred to as a wireless personal area network (WPAN), provides a wireless communication network for interconnecting devices locally around an individual person. For example, WPAN technology may serve to interconnect the now ubiquitous cell phone with other electronic and communication devices that many people may encounter at their work place, such as printers, scanners, copiers, “wired” multi-line telephone sets, keyboards, mice, etc.; or during personal activities such as exercising, shopping, or dining, such as exercise machines, cash registers, cycling speedometers/odometers, pedometers, automated menu systems, etc. WPAN technology may even serve a more specialized purpose, such as in health care, where wireless sensors may be placed on or near a patient to allow medical professionals to monitor that patient—whether that patient is actually in a medical care facility such as a hospital or remotely through the use of a cell phone or other wireless communication device carried around by that patient.
In order for devices to wirelessly communicate with each other, they must be able to synchronize their timing as well as identify each other. Thus, one key aspect of any communication system is timing acquisition, where a receiver acquires precise timing information regarding a transmitter. Acquisition is typically accomplished by the transmitter sending a mutually shared preamble sequence and the receiver constantly checking for the presence of this sequence, where one way of achieving synchronization is through transmission of predefined sets of signals preceding data in a transmission between the devices. For example, transmission of each data packet by a transmitting device may be preceded by a transmission of a structured sequence of alternating 1's and zeros to allow a receiving device to synchronize its local clock with that of the transmitting device. These transmitted structures are generally referred to as preamble structures.
The characteristics of a good timing acquisition algorithm include accuracy, low power consumption, immunity to interferers, and low complexity/memory requirements. Specifically, in low power duty-cycled communication systems such as ultra wideband systems, acquisition accounts for a significant part of the power consumption at the receiver node. Existing methods of timing acquisition tend to use a known fixed or pseudo-random sequence of a pre-determined length, usually independent of the data rate mode. At the receiver, acquisition algorithms are based on the concept of maximizing correlation, which tends to provide accurate timing as well as good interference immunity. However, these approaches are typical not generally memory efficient, and also do not scale well in variable data rate systems because of their complexity and operational latency. Further, although existing approaches for creating preamble structures involve generation of preamble sequences that have good correlation properties, only some of these preamble sequence generation approaches also take into account resource use on the receiving device to allow for efficient detection of these preamble sequences. Fewer still of these preamble sequence generation approaches can also support creation of a large universe of possible preamble sequences having these good correlation properties to be able to support a large number of devices.
In order to be able to support a large number of devices with distinctive preamble sequences that allow efficient acquisition on the receiver and the other desirable properties as mentioned above, other approaches are desired.